Observations of self-aggregation and dissociation of E. coli ribosomes by optical mixing spectroscopy

Measurements of the diffusion coefficient of E. coli ribosomes by the technique of optical mixing spectroscopy are used to show that these ribosomes, when incubated in a 4°C cold room, undergo a slow aggregation with time. Even in the presence of this aggregation, it was possible to observe the diffusive character of the single 70s ribosome. It was found that at high (≥0.100 molar) KCl concentrations the ribosomes broke into their subunits. At moderate KCl concentrations they were relatively stable and at a very low KCl concentration (0.005 M) they were observed to dimerize. The values of the diffusion coefficients of the 50s subunits, the 70s single ribosome and the ribosome dimer determined in these measurements are consistent with currently accepted values.     

Garra tibanica ghorensis subsp.nov. (Pisces: Cyprinidae), an African element in the cyprinid fauna of the Levant

Garra tibanica ghorensis subsp. nov. is described from the southern Dead Sea Valley. In the Levant it represents the only cyprinid fish with African affinities known to date. It is suggested that G. t. ghorensis reached the area of its present distribution from the south and is not to be regarded as a relict of an earlier migration of the species to Africa via the Levant.Results of the travels of R. Kinzelbach to the countries of the Middle East, No. 18.Results of the travels of R. Kinzelbach to the countries of the Middle East, No. 18.     

Sexual reproduction and early development of the solitary coral Fungia scutaria (Anthozoa: Scleractinia)

Fungia scutaria spawned vigorously with a lunar beriodicity during the summer months of 1981 and 1982. Spawning activity declined in the fall of both years and was absent in winter and spring (1983). There was only one short spawning event per lunar cycle. Each event occurred in the evening between 1700 and 1900 hours 1 to 4 days following the full moon. Fungia scutaria exhibits gonochorism. Females ejected eggs through their mouths into the seawater above. Many of these negatively buoyant eggs settled onto the oral discs and were moved off the edge by ciliary-mucoid activity. Spermatoza from males were similarly expelled in a jet of gastrovascular fluid. Spawned eggs were small and lacked endosymbiotic zooxanthellae. Rapid development led to ciliated solid planulae by the next morning. Within 24 h a mouth had begun to develop. Planulae may have been able to feed within 39 h. Infection with zooxanthellae occurred 4–5 days following spawning. Planulae may have become competent for settlement by 7 days, but attempts to docment settlement produced ambiguous results.     

Brief International Cognitive Assessment for MS (BICAMS): international standards for validation

ABSTRACT: An international expert consensus committee recently recommended a brief battery of tests for cognitive evaluation in multiple sclerosis. The Brief International Cognitive Assessment for MS (BICAMS) battery includes tests of mental processing speed and memory. Recognizing that resources for validation will vary internationally, the committee identified validation priorities, to facilitate international acceptance of BICAMS. Practical matters pertaining to implementation across different languages and countries were discussed. Five steps to achieve optimal psychometric validation were proposed. In Step 1, test stimuli should be standardized for the target culture or language under consideration. In Step 2, examiner instructions must be standardized and translated, including all information from manuals necessary for administration and interpretation. In Step 3, samples of at least 65 healthy persons should be studied for normalization, matched to patients on demographics such as age, gender and education. The objective of Step 4 is test-retest reliability, which can be investigated in a small sample of MS and/or healthy volunteers over 1-3 weeks. Finally, in Step 5, criterion validity should be established by comparing MS and healthy controls. At this time, preliminary studies are underway in a number of countries as we move forward with this international assessment tool for cognition in MS.